1. Field of the Invention
The present invention relates to a display driving device in an electronic device operated by a microprocessor built therein and, more particularly, to a display driver having a display memory for storing display data.
2. Description of the Related Art
In the conventional electronic data bank, for example, a key input section and display section are provided. Address data and schedule data which are previously input and stored in a semiconductor memory by the key operation are read out and displayed on the display section when required.
Generally, a liquid crystal display unit is used as the display section of this type of electronic device. Display data stored in a RAM used as the display memory is read out and output to the display section as follows as an instance. In particular, assume that an 8-bit data processing microprocessor is used and the liquid crystal display unit is constructed by 160 dots in height.times.128 dots in width, for example, and that, when an 8-bit data bus is connected thereto and display data is transferred from the RAM, the 8-bit data readout operations must be repeatedly effected 16 times in order to transfer one line of display data in a horizontal direction.
However, if the readout processes for 8 bits are repeatedly effected for the display memory as described above, it takes a long time to read out the entire display data, and the power consumption becomes large since a large number of memory accesses must be effected.